Emanttel rawson



April 9, 1929. E, RAWSON 1,708,738

AUTOMATIC CONTROL VALVE Filed Oct. 29, 1.927

ATTORNEY.

Patented Apr. 9, 1929.

UNITED STATES PATENT OFFICE.

EMANUEL nAWsoN, or carence, .traditoreL Assreivon To THE SUPERHEATER comrana, or NEW YORK, N. Y.

AUTOMATIC CONTROL VALVE.

Application filed October 29, 1927. Serial No. 229,725.

l My invention relates to automatic control valves, and has particular reference to the type oi' valve used to prevent the starting or continued operation ot' a fluid pressure driven pumping unit under no load conditions. Specifically, the invention is in the nature or an improvement upon the invention described and claimed in my copending application, Serial No. 217,118, filed Septomber 2d, 1927, designed to improve the operating characteristics of the control valve undercertain service conditions. The detailed objects of the invention, together with the advantages to be derived from its use, Will appear trom the following detailed description of a preferred form of the invention applied to a steam driven centrifugal pumping unit used as the feed Water pump for a locomotive.

ln the accompanying drawings' forming a part hereof, Fig. 1 is a 'fragmentary elevation of a locomotive equipped With such a iced Water pump to which the invention has been applied; Fig. 2 is an elevation, partly in section, on an enlarged scale showing the pump and valve assembly; and Fig. 3 is a section on a still larger scale of a detail oi the apparatus.

Referring now to the drawings, the pumping unit indicated 'at 1 comprises a steam driven turbine rotor 2 directly connected to the vane of a centrifugal pump 3, the turbine and pump being mounted in a single housing. The turbine is supplied With steam through the conduit 41 controlled by the throttle 5 and having located therein the valve casing 6 between the throttle 5 and the turbine. The pump is supplied with Water through the inlet conduit 7 and discharges through conduit 8 to the check valve (not shown) of the boiler.

The valve 9, adapted to control flow through the conduit 4l, is mounted in the casing 6, the latter carrying a capped bonnet 10 forming a cylinder in Which is located the piston. 11 mounted on the end of the stem ot valve 9. A spring 12 below piston 11 holds valve 9 normally in open position.

Between throttle 5 and valve 9 the inlet conduit 4 is provided with a manually operable Vvent valve 13, the purpose of which will appear hereinafter.

The casing 6 on theV inlet side of valve 9 is provided with a restricted opening 111 from vvhich the conduit 15 leads to the hydraulic control unit situated Within the pump housing. The hydraulic control unit comprises a casing 16 forming a closed chamber 17 connected with the discharge side of the pump 3 through the passages 18 and' .19. The top of chamber 17 is defined bv a ilexible'diaphragm 20 suitably secured.7 in the casing 16, said diaphragm serving to support a cylindrical valve member 21 slidably mounted in the housing 16 and having a conically faced upper end adapted to engage a seat formed Within the casing 16 to separate the chambers 22 and `23. Intermediate its ends the valve member 21 is provided With an annular recess registering with an atmospheric vent in casing 16 to prevent the building up of pressure on top of the diaphragm 20 due to leakage.

The Vconduit 15 leads from the restricted opening 14@ in casing 6 to the chamber 23 above the hydraulic valve member 21` and the lower chamber 22 is connected by means of a conduit 24 to the chamber above the piston 11 actuating the valve 9.

An automatic timing valve is located in conduit 241 and,as is shown more clearly in Fig. 3, the timing valve comprises a casing 25 forming a chamber 26 opening through the port 27 to the passage 28, the latter being connected `by means of a suitable drain pipe 29 to the atmosphere. The conduit 2st is connected to chamber 26 so that the latter forms a part of the connection between the hydraulic control valve and the piston 11. The port 27 is controlled by a valve 36 resiliently held in open position by the spring 31, the latter being carried by a suitable recessed spider 32 :forming part oit the casing 25. As will be clear from Fic'. 3, the valve 3() vvill be held in open positiokii by the spring 31 until apredetermined pressure is built up in chamber 26, thereby providing an atmospheric vent for the conduit 2a when the pressure in the latter is belovv a certain value.` lli/Then the pressure in rchamber 26 exceeds'this value, it will serve to close valve 30 against the action oit spring 31 to close the vent.

The operation el' the device is as follows: Assuming the pump not in operation with water available in the conduit 7, opening of the throttle 5 permits steam to flow to the pump turbine through the valve 9, which is held in open positionby spring 12. At

the same time steam is permitted to {iow into conduit 15 throuo'h the restricted opening'` 14, but due to the restriction the steam 'liowinto the conduit is atv acompa tively slow rate. f Steam delivered by conc uit 15 ilows from chamber 23 to chamber, 2,2y

28, and appreciably delays the lowofsteain through the remainder ol" conduit, 24, toL the chamber above piston 1l.

During; the interval of time be'lore steam can reach piston 11, caused by the delay action of the restricted opening 14 and timing valve 30, the pump 3 builds up a discharge pressure whichl is communicated to the, underside ofdiaphragm QQIanud. acts to lift the valve member 21 to shut olf communication between chambers Qand 22. lt will thus be seen that it water is available at the suction side of the pump when the latter is st rted, steam flow to the piston 11 will be :closed bythe hydraulic valve member before a pressure is built up sufficient to overcome the action of spring 12 andiclose the valve Sto shut oil-the steam supply to the pump. H' operating conditions remain normal, that is, a continuedsuplply o'iwater is received byy theupumthe apparatus will continue to operate, in theA manner just described with the hydraulic valve member 21 preventing thel flowA of steam to the con-` trol valve` 9 and permitting continued steam flow to the turbine.l v

y It, now, the water supply tothe pump fails, the resultant laclr of pressure in the pump discharge'line will allow the valve memberl to be forceddownwardly by the pressure otsteam in chamber 23, thus establishiiig` communication between. the conduit l5 andapiston 1l. rhe 'timing valve 30 in this instance wilL permit. an init-al escape ot stcamtopthoatmosphere, but upon the lmilding upwot pressure in chamber 2G this valve will close and steam will pass on,

through thehconduit-24 to act onpiston 11, closing valvev9-and shutting oil' the pump.

It' for any reasonthe automatic valvev 9 closed, and the throttlevis subsequently closed, it will be seenl that an appreciable quaritityfof steam under pressure will Vbe trapped in the steamV supply conduit -4 between the two valves, and ,the pressure of this 'steam Ycommunicated to the pistonV 11 through conduits 15 and 24 will serve to4 hold the valveQ` closed .position until ,the Vtrapped steampcondenses. Untilsuch condensation' 'takes place, itY would beV impossible restart the pump, and'in orderto `avoid such delays and ,make it impossible vto immevdiately restart the pump after valve'iQ has ywill escape through beenclosed l` have providedzthc vent valve 13 for the purpose of releasingz, this trapped steam and allowing the valve 9 to open.

" 'lt it is attemptedr to start the ypump when no water is available in the conduitr, the actionl orl the control valve will be substantially thel same as that previouslyV described whenl the water supply fails with the pump in operation, as steam will pass immediately, except for` the dela-y occasioned byl restriction 14 and valve 30., through con.- duits l'and 24 tothe piston 11, and close the c ont-:rolvvalvke 9. l 'Y i `v The delay action provided is necessary to permit the starting`v of the pump when water is available, 'for st in werev per,- mittedto new without delayi'romthe inlet conduit 4 to the piston 11,'it would. close, the valve 9and shut down the pump before the latter had. hadusulicient `'time to build, up a hydraulic,y discharge pressure sufficient to actuate, the'valvefmember 21 and close communication between` conduits 15 and 24. l

The general arrangement of pumpy and control valve described is similar. tof` that shown in my copending application hereinbetore referred to exceptlor the provision of the timing valveO, which I have found necessary to the 4satisfactory operation of the device under all conditions. In the prior form delay action was secured; Vby means ol an expansion chamber placed in the condui Q15, butiinder certain operating` conditionsthe steam trapped .in such a 'chamV` ber will flow past' the vopen valve 2l and close the main valve 9 when such action is notdesired.v Viti the present arrangement theamount oit steam inconduit 15 is comparatively small, and this steainis vented to the atmosphere through lvalve 30 .underfconditions which. permitted steam from :anexparisien chamber in conduit 15 to close the mainvalveV9.v

For example, it the pump running` under normalconditions is shut down by closing throttle 5, they action is as follows: Thejclosing of the throttle causes an inunediate drop pressure in conduit 4, and also a very rapid loss of pressure in the chamber` 17, permittingthe valveQl to open. The-re- ,striction 14` does not, however, permit a rapid returny flow of steam fromthe conduit 15V to the conduit4 in which thel pressure has dropped, and this steam is free because of the openingiof valve/21 to flow towardthe piston '11,'V In cases. whereA an, expansion chamber is used, this steam is'suiicient.` in quantity to actuate piston 11 ,and vrclose valve 9,therebyy preventingy reSHting of thepump until condensation of thesteain ltalsjplace. With the present arrangement the small quantity, of steam trapped iin- 'thevconduit 15 the til-Il lg Valve .SQand have no effect on piston 11.

It will be obvious that the amount of delay secured before steam reaches piston l1 will be determined by the strength of the spring 31 governing the action of the timing valve 30, and I have found that for centrifugal pumps of the type employed a spring pressure of about twelve pounds acting on valve 30 to hold it open gives the correct timing delay.

Furthermore, it will be evident that the timing valve may be placed in conduit l5 instead ot conduit 24 Without affecting the operation of the device, but I prefer to locate it in conduit 24, as in this position it is open when the pump is in normal operation, while if in conduit 15 it Would be closed and subject to steam pressure Whenever the pump operated.

Obviously, the control valve mechanism shown in the illustrative embodiment may be applied to many different forms of prime movers, and many changes and modifications in the specific arrangement shown may be made Without departing from the spirit of the invention, which is to be considered as including all that may fall Within the scope of the appended claims.

I claim:

l. An apparatus of the class described, a turbine, a pump driven thereby, a conduit connecting said turbine With a fluid pressure source, a throttle located in said conduit, a control valve located in said conduit between said throttle and said turbine, a iluid pressure actuated means for closing said control valve, a hydraulic control unit comprising a valve adapted to be closed by the discharge pressure from said pump, a connection leading from the inlet side of said control valve to the valve in said unit, a connection leading from said last-named valve to said fluid pressure actuated means, an opening venting one of said connections to the atmosphere, and a valve controlling said opening, said valve being closed by a predetermined pressure in said connections. 2. In apparatus of the class described, a turbine, a pump driven thereby, a conduit connecting' said turbine With a fluid pressure source, a throttle located in said conduit, a control valve located in said conduit between said throttle and said turbine, fluid pressure actuated means for closing said control valve, a hydraulic control unit co1nprising a valve adapted to be closed by the discharge pressure from said pump, a connection leading from the inlet side of said control valve to the valve in said unit, a connection leading from said last-named valve to said pressure actuated means, an opening venting said last-named connection to the atmosphere, and a valve closed by a predetermined pressure in said last-named connection for controlling said opening.

3. In apparatus of the class described, a turbine, a pump driven thereby, a conduit connecting said turbine With a fluid pressure source, a throttle located in said conduit, a control valve located in said conduit between said throttle and said turbine, Huid pressure actuated means for closing said control valve, a hydraulic control unit co1n prising a valve adapted to be closed by the discharge pressure from said pump, a connection leading from the inlet side of said control valve to the valve in said unit, a connection leading from said last-named valve to said pressure actuated means, an opening venting said last-named connection to the atmosphere, a valve controlling said opening, said valve being constructed and arranged to be closed by fluid pressure in said connection, and a spring for holding said valve in open position until a predetermined pressure is reached in said connection,

EMANUEL RAWSON. 

